1. Field of the Invention
The present invention relates to a biological cell destruction device. More particularly, the present invention relates to a neoplasm cell destruction device utilizing low frequency sound waves to disrupt or displace cellular materials in neoplastic cells so as to damage and ultimately destruct the neoplastic cells without destructing surrounding healthy cells by virtue of the neoplastic cells trading in their ability to heal themselves if damaged in return for uncontrollable reproduction whereas the healthy cells can repair themselves if damaged and thereby eliminating a need for target finding apparatus.
2. Description of the Prior Art
High frequency acoustic waves or ultrasound may be used to remotely heat industrial or biological materials. There has been strong evidence in research and clinical laboratories that focused ultrasound for cancer hyperthermia will become a useful mode of treating cancer patients, in addition to the surgical, radiological, and chemotherapeutic methods that are available now.
In the treatment of tumors in cancer hyperthermia, focused ultrasound heats the tumor to a temperature of approximately 43° C. while the adjacent healthy tissue is kept at a lower temperature, closer to normal body temperature (37° C.). The elevated temperature in the tumor disrupts the tumor growth and eventually kills it. This allows the cancer to potentially be treated without surgery, without ionizing radiation, or without chemotherapy.
Conventional focused ultrasound for heating is employed by using either a scanned ultrasound transducer or with a phased array. The scanned transducer uses a lens, much like an optical magnifying glass focus sunlight, while the phased array uses electronic delays among the array elements to achieve focusing. A burst of sound is then emitted which converges at the focus to provide localized high intensity acoustic energy. Some of the high energy acoustic energy is absorbed by the tissue at the focus and is dissipated as concentrated focal heat. The rest of the energy travels through the focus and is slowly dissipated into the surrounding tissues as distributed heat.
Biomedical hyperthermia applicators using a plurality of sound sources to heat larger, distributed volumes, have also been investigated. These investigations have relied upon linear thermal superposition of the plurality of sound sources to heat the target tissue. Nonlinear effects of sound propagation through animal tissue and materials have also been studied for a single sound source.
The nonlinear mixing, or intermodulation, of sound waves has been known in oceanographic acoustics. Oceanographic acoustic applications have used both the linear (superposition) and the nonlinear (intermodulation) effects of intersecting sound beams. Nonlinear acoustic sonars, known as oceanographic parametric sonars, deliberately promote the generation of a difference frequency to enhance sonar beam forming and long range sound propagation. The generated difference frequency is usually 30 to 60 dB below the level of the primary frequencies. A second product of nonlinear mixing is the sum frequency, which is generated by the intermodulation process at 10 to 40 dB below the level of the primary frequencies, indicating that the conversion from primary to sum frequency is a significantly more efficient process than the conversion of a primary to a difference frequency. Since higher frequencies are subject to higher absorption coefficients in water, they generate more heat than the primary frequencies as they propagate, but propagate shorter distances than the primary frequencies. In oceanographic sonar applications, heat generation via sound absorption is generally an undesirable result of nonlinear intermodulation.
It is generally recognized that the use of microwave energy to produce moderate internal heating is an effective tool in the treatment of tissue, especially neoplastic tumors. The primary factor limiting such treatment in the past has been the difficulty of delivering the heat to a target region below the skin surface. Of course, it is possible to use an interstitial source, but this method has the drawback of being invasive. Because of this limitation, noninvasive treatment to date has largely been confined to treatment of surface tumors since it is difficult to heat deep tumors without also heating the intervening tissue.
In order to get significant heating in tumors more than a few millimeters below the skin surface, the field from a single source at the skin surface will have to be high and therefore painful. One approach has used a moving source, generally activated by switching discrete sub-arrays of sources. The moving source, however, results in an incoherent summation of energy at the tumor site. While tending to reduce the heating effects in the intervening tissue, this method has not eliminated the heating of the intervening tissue or reduced it to an acceptable level.
Additionally, to insure that the desired volume of tissue is potentially heated, an operator must not only know the characteristics in the area of interest, but also be able to determine which tissues are being heated. Currently, the ability to make this determination depends on the use of an interstitial probe or a radiometer. The current method also does not allow for imaging of the area, except to use other modalities, such as CT, MRI, ultrasound, etc. Such methods, while noninvasive, do not provide appropriate characteristics of the area and tissue to maximize the heating of the target tissue with microwaves.
Most cancer cells during metastasis are rapidly killed by mechanical trauma, associated with shape-transitions, which requires increases in cell surface area. L. Weiss, J. P. Harlos, and G. Elkin; Int. J. Cancer 44; 143-148 (1989).
The hypothesis has been advanced that such increases in surface area occur in two phases. First, there is an apparent increase as a result of surface unfolding, which is reversible and non-lethal. Second, there is a true increase, during which cell surface membranes are stretched, with an increase in membrane tension. When tension exceeds a critical level, the surface membranes rupture and the irreversible change is lethal.
Numerous innovations for destroying biological tissues have been provided in the prior art that will be described. Even though these innovations may be suitable for the specific individual purposes to which they address, however, they differ from the present invention in that they do not teach a cancer cell destruction device utilizing low frequency sound waves to disrupt or displace cellular materials in cancerous cells so as to damage and ultimately destruct the cancerous cells without destructing surrounding healthy cells by virtue of the cancerous cells trading in their ability to heal themselves if damaged in return for uncontrollable reproduction whereas the healthy cells can repair themselves if damaged and thereby eliminating the need for target finding apparatus.
For example, U.S. Pat. No. 5,144,953 to Wurster et al. teaches a lithotritor with an X-ray alignment system that includes a transducer for generating focused ultrasonic shock waves adapted for alignment on a concretion or tissue to be destroyed. The transducer is connected to an image-forming diagnostic X-ray system for locating the concretion or tissue and includes an X-ray emitter and an image intensifier disposed on a pivotable frame. The transducer is connected to the X-ray emitter which in turn is disposed at the center of the transducer, so that the emission axes of the transducer and the X-ray emitter coincide.
Another example, U.S. Pat. No. 5,222,484 to Krauss et al. teaches an apparatus for shock wave treatment that includes a shock wave transducer with a cup-shaped body and with an X-ray location finding device for finding the location of a bodily concretion or tissue to be treated. The X-ray device includes an extendable X-ray tube with telescoping tube sections which are sealed against an acoustic coupling medium filling the delay path of the transducer by a balloon filling arranged within the X-ray tube. The balloon is secured to the upper section of the tube and to the lower section thereof. Over pressure or under pressure is applied to the interior of the X-ray tube to adjust its length in order to optimize X-ray location finding on the one hand, and shock wave treatment on the other hand.
Still another example, U.S. Pat. No. 5,388,581 to Bauer et al. teaches a therapy apparatus for treating concretions and tissue in the body of a patient by means of sound waves. The apparatus includes a sound wave generator and an available X-ray device for locating an object for therapy. The therapy apparatus has a spot film device that is arranged within the axial passage of an X-ray cone. The available X-ray device is attached to the sound wave generator, with its central longitudinal axis aligned with the focus thereof so as to be able to precisely adjust and fix the X-ray device to the therapy apparatus quickly and safely.
Yet another example, U.S. Pat. No. 5,498,236 to Dubrul et al. teaches a catheter suitable for introduction into a tubular tissue for dissolving blockages in such tissue. The catheter is particularly useful for removing thrombi within blood vessels. In accordance with the preferred embodiments, a combination of vibrating motion and injection of a lysing agent is utilized to break up blockages in vessels. The vessels may be veins, arteries, ducts, intestines, or any lumen within the body that may become blocked from the material that flows through it. As a particular example, dissolution of vascular thrombi is facilitated by advancing a catheter through the occluded vessel with the catheter causing a vibrating stirring action in and around the thrombus usually in combination with the dispensing of a thrombotic agent, such as urokinase into the thrombus. The catheter has an inflatable or expandable member near the distal tip which when inflated or expanded, prevents the passage of dislodged thrombus around the catheter. The dislodged portions of thrombus are directed through a perfusion channel in the catheter where they are removed by filtration means housed within the perfusion channel before the blood exits the tip of the catheter. Catheters that allow both low frequency (1-1000 Hz) vibratory motion and deliver of such agents to a blockage and a method for using such catheters are disclosed.
Still yet another example, U.S. Pat. No. 5,501,655 to Rolt et al. teaches an ultrasound hyperthermia applicator suitable for medical hyperthermia treatment, and method a for using it. The applicator includes two ultrasound sources producing focused ultrasound beams of frequencies f0 and f1. An aiming device directs the two ultrasound beams, so that they cross each other confocally at the target. A controller activates the two ultrasound sources, so that the target is simultaneously irradiated by the two focused ultrasound beams. The two ultrasound sources provide acoustic energy sufficient to cause sufficient intermodulation products to be produced at the target as a result of the interaction of the two ultrasound beams. The intermodulation products are absorbed by the target to enhance heating of the target. In preferred embodiments, the ultrasound sources include a pair of signal generators for producing gated ultrasound output signals driving single crystal ultrasound transducers. In other embodiments, the ultrasound sources include a pair of phased array ultrasound transducers for generating two separate ultrasound beams. An aiming device is provided for electronically steering and focusing the two ultrasound beams, so that they cross each other confocally at the target. Further embodiments employ pluralities of transducers, arrays, or both.
Yet still another example, U.S. Pat. No. 5,503,150 to Evans teaches a method and apparatus for noninvasively locating and heating a volume of tissue, specifically a cancerous tumor. The method includes placing a bolus in contact with the patient and substantially around an area of interest including the volume of tissue, placing an array of antennas on the bolus and substantially around the area of interest, imaging the area of interest, selecting an approximate center of the volume of tissue on the initial image, determining approximate amplitudes and phases for the antennas, energizing each element at respective appropriate amplitudes and phases to heat the volume of tissue, imaging respectively the area of interest to create subsequent images, and subtracting the initial image from the subsequent images to determine temperature changes in the area of interest.
Still yet another example, U.S. Pat. No. 5,524,625 to Okazaki et al. teaches a shock wave generating system capable a forming a wide concretion-disintegrating region by energizing ring-shaped transducers and a hyperthermia curing system. A width of a focused region synthesized from a plurality of focal points formed by a plurality of shock waves is varied by properly controlling delay times and/or drive voltages for a plurality of ring-shaped piezoelectric transducer elements. The shock wave generating system includes a shock wave generating unit having a plurality of shock wave generating elements and a driving unit for separately driving the plurality of shock wave generating elements by controlling at least delay times to produce a plurality of shock waves in such a manner that a dimension of a focused region synthesized from a plurality of different focal points formed by the plurality of shock waves is varied in accordance with a dimension of a concretion to be disintegrated which is present in a biological body under medical examination.
Finally, yet still another example, U.S. Pat. No. 5,542,906 to Herrman et al. teaches a therapy apparatus that has a source of acoustic waves which generates acoustic waves focused onto a focus and an X-ray locating means with which the subject to be treated can be irradiated from different directions. The central ray of the locating means assumes a first direction for a first irradiation direction and a second direction for a second irradiation direction. The apparatus has a positioning system with which the subject to be treated and the focus can be adjusted relative to one another. The region to be treated and the focus are adjustable relative to one another by synchronous actuation of the positioning system in two adjustment directions for at least one irradiation direction. The adjustment taking place in a direction that proceeds parallel to the direction of the central ray that belongs to the other irradiation direction.
It is apparent that numerous innovations for destroying biological tissues have been provided in the prior art that are adapted to be used. Furthermore, even though these innovations may be suitable for the specific individual purposes to which they address, however, they would not be suitable for the purposes of the present invention as heretofore described.